Orally rapidly disintegrating tablets have been developed as a form which is easy to be taken by patients, elderly people, children, etc. who have difficulty in swallowing drugs, or is easy to be taken without water. The orally rapidly disintegrating tablets should have such a sufficient hardness as not being chipped or dusted during production or transportation of tablets or opening, and in addition, it is required that a disintegration time in the oral cavity is within about 60 seconds and a texture and taste in the oral cavity has no problem. There are more problems to be solved in the orally rapidly disintegrating tablets compared to normal tablets. Specifically, a disintegration time and hardness are contradictory factors, and in general, disintegration times tend to be extended as molding pressures are increased for the purpose of the increase of hardness, and hardness tends to be decreased as molding pressures are decreased for the purpose of the shortening of disintegration times.
An orally rapidly disintegrating composition which is prepared by granulating an organic acid such as tartaric acid, a hydrogen carbonate salt of alkali metal such as sodium hydrogen carbonate, a network maintenance agent such as cornstarch or potato starch, a color protection agent such as mannitol or xylitol, followed by compressing to mold has been known (Patent Document 1). The composition becomes fizzy by the reaction of an organic acid with a carbonate salt under moisture condition in the oral cavity, and a drying process is required to prepare the composition in addition to the compression molding process.
An orally rapidly disintegrating formulation which is prepared by dry-blending hydroxypropylstarch, spray-dried D-mannitol, a physiologically active ingredient and anhydrous silicic acid, followed by compressing to mold has been known (Patent Document 2).
An orally rapidly disintegrating tablet comprising a pharmaceutical composition obtained by dispersing sugar and an inorganic compound in water and spray-drying (Patent Document 3), and a composition for an orally rapidly disintegrating tablet characterized by dispersing complex particles of sugar, a disintegrant and an inorganic substance in the presence of water (Patent Documents 4, 5, 6) have been known.
It has never been known that a disintegrating particle composition which is prepared by dispersing inorganic excipient(s) and starch(es) in complex particles which are composed of mannitol and xylitol, and an orally rapidly disintegrating tablet comprising the composition have better molding properties, hardness and disintegrating properties than those prepared by the conventional method.    [Patent document 1] JP-A-11-310539    [Patent document 2] JP-A-2005-306770    [Patent document 3] JP-A-2000-86537    [Patent document 4] WO 2005/37319 pamphlet    [Patent document 5] WO 2005/37254 pamphlet    [Patent document 6] WO 2007/29376 pamphlet